Evaporator for gas developing machines



March 10, 1953 G. WILDE 2,630,744

EVAPORATOR FOR GAS DEVELOPING MACHINES Filed Jan. 16, 1950 Qi W- 31 INVENTOR.

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25 1 6 BY W HTTORNEY Patented Mar. 10, 1953 UNITED STATES PATENT oFFIcE EVAPORATOBJ FOR GAS DEVELOPING MACHINES Frederick. G. Wilde, Rochester, N. Y., assignor to Paragon Revolute Corporation, Rochester, N. Y"-, acorporationofj New York Application January 16, 1950, Serial No. 138;!164

7, Claims.

i 9 This: invention. relates: to x a combined photographicprintingand developing: machine: of. the so-called dry developer. type, which utilizes. ammoniaagas. orthe. like: and is. a. continuation-inpart of my. copending application Serial Number 109,298, filed August 9, 1949.

Where aprinterand a developer of this type are" incorporated in a: single cabinet much diifi cnlty. hasmbeen. encountered in obtaining satisfactoryiprints throughout the wide range "of required speeds. at which thephotosensitive paper to: be. printed, 'isrpassed through the machine. For" example, if: the speed of the machine is slowed down, as is frequently required in the printing of certain types" of tracings, there is danger of too. much moisture accumulating in the. printed photosensitive; paper, with, the: result". that the surface of the; finished print will be wavy or wrinkledand the appearance oithe print will be otherwise marred by water stains. It. has been discovered that the stains. andpthe l'aclc of uniformity in-thesurf'ace smoothness of the prints. produced at. various speeds, has been due to the fact that the moisture. and heat distribution through. the combined. printer and developer cannot properly be regulated: with the present devices and that the evaporation of the aqua: ammonia cannotmbe. controlledwith the required nicety.

In: accordance with. the present: invention, an aquaamm'onia evaporator located in atemperaturecontrolled atmosphere, is so constructed that proper moisture conditions: can be: maintained within. the.- developing. chamber. at: all times; .and yet: the: rate: of eyaporationofi the: aqua ammonia as; wellxas; the rate; of. evaporationof. the water therein can be independently and. accurately controlled to correspond with i the predetermined speed of. travel of the printed. photosensitive sheet to be developed thereby.

The various features and advantages of the invention will appear from the detailed description and claims when taken with the drawings in which:

Fig: 1 is an end viewof the upper portion of a combined printing and developing machine in. accordance withthe present invention;

Fig. 2 is a detailed side view of the evaporator unit to be used in the machineotFig. 1;

Fig. 3 is a plan view of the. evaporator unit illustrated in Fig. 2;

Figs. 4 and 5 are transverse sections of the evaporator unit taken substantially" on the: line 4-4 and 5-43, respectively of Fig-.2;

Fig; 6. is. a'z'side. elevationalview. with: exaggerated spacing of the. trays of amddifi'ediorm of the evaporating unit; and

Fig. '7 is an end view of this modified unit.

Referring to Fig. l there is. diagrammatically illustrated, a combinedprinting and. developing machine of the present invention. This machine comprises a closed. cabinet 5 ofwhich only the upper portion is shown, and. of which one end thereof, is removed. The. printing unit of the machine comprises a glass cylinder 6 mounted within the lower part of the cabinetfo'r' rota.- tion around a horizontal axis, on suitable means (not shown). A light source generally desig.-'- nated L, extends substantially along the. main axis of the glass cylinder. This cylinder is rotated by a wide, driven belt 8. or it can be driven by a series of. parallel narrow belts engaging a substantial portion of the, cylinder, the belt. having a path of travel definedby the. rollers 9, H), H, l2 and I3, one of. which rollers is driven from a suitable; source (not shown). The front of the cabinet as illustrated at the left otliig. 1, is provided with a shelf l4 over which. a strip of photosensitive paper or cut sheets can be inserted to pass through the machine along apath indicated by the arrows. Tracings to be printed are laid on. the portion of the sheet passing over the shelf. The advancing. sheet. and the. superimposed tracing pass under the guide. plate. [5 to be. drawn by the cylinder 6 and the engaging belt 8 inv exposure position around the light source L. It will be. understoodthat the length of the exposure. is determined, in part, by the speed of. travel. of the. tracing and photosensitive strip through the machine, this speed being adjusted by well-known. mechanism. (not shown).

After exposure. the tracing. drops. into. the re..- ceiving tray It. In order to. prevent. the traciing from continuing to cling to the, cylinder, a separator brush ll mounted on the rear edge of the tray is disengages the tracing fromthe cylinderand directs the tracing into the tray. The exposed portion of the photosensitive. paper continues to be moved along bythe belt Briding on the guide l9, into the developer unit. As, more fully disclosed in the Patent 2,475,809 granted to Sullivan et al. on July. 12,1949, this unit.com. prises a gas chamber C closed at its endsand .front by the end walls of the cabinet and by the chamber wall 20 respectively, thewall 29 terminating in spaced tubular guide members 2| coextensive with the length of the chamber. The rear of the chamber between the guide members '2 I has a; rectangularopening which is sealed by a, traveling. rubber belt 22. which rides. on; the

spaced guide members 2! and guide rolls 23. The

belt and the rolls 23, guide the printed portion of the photosensitive sheet over the opening in the rear of the chamber C where this portion of the sheet is developed by the ammonia gas passing between the rolls 23 as more fully disclosed in the mentioned patent. After bein developed, the mentioned portion of the paper is guided to the receiving tray 24. The developing ammonia gas in the chamber C is supplied by an evaporator E to be described, to which aqua ammonia is pumped from a suitable source.

In the use of machines of the so-called dry developer type, much difiiculty has been encountered in the production of satisfactory prints when the speed of the machine has to be slowed down to effect desired exposure of certain tracings or originals. It has been discovered that the cause of this difficulty arises from the fact that changes in speed of the machine, frequently require changing to a different optimum relation between the following factors: (1) the temperature within the chamber, (2) the temperature of the paper being developed, (3) the amount of water vapor within the chamber and (4) the concentration of ammonia gas therein. It will be understood that if the temperature within the chamber changes, the dew-point therein will also change so that moisture demands in the machine will change accordingly. The moisture in the chamber is supplied by evaporation of the Water in the aqua ammonia at the same time that the ammonia gas is given off. However, the optimum relation between moisture and gas, changes with the speed of travel of the paper but this fact has not been recognized in prior machines of this type, or if recognized, no provision has been made to effect the necessary change.

In accordance with the present invention a novel evaporator for aqua ammonia is provided which in combination with heat removal to be described, overcomes the difficulties of former machines. This evaporator comprises a V-shaped trough 25 which gently slopes downward from left to right (Fig. 2) where its lower end has a discharge opening 26 located above a waste pipe or the like (not shown). The aqua ammonia is intermittently supplied by a pump or the like (not shown) to an evaporator pipe 21 which is perforated on its upper side. This pipe which extends in superimposed parallel relation with the deepest part of the trough, first slopes downward toward the right end of the trough (Fig. 2) and then gradually slopes upward toward the left end thereof. At that point, the pipe discharges into the left end of the trough. With this shape of the evaporator pipe 21, a pool of aqua ammonia, is continually maintained therein so that substantially all of the ammonia gas is evaporated from the aqua ammonia in the evaporator pipe and only water with a trace of ammonia gas therein is forced out of the left end of the pipe to discharge into the high end of the trough 25. This water, as it flows downward in the trough, is evaporated in amounts necessary to satisfy the moisture requirements in the chamber while the excess water is discharged through the opening 26. The controlled evaporation in the trough, of the water with some ammonia gas therein, is effected by an electrical heating element 25 extending generally along and above the trough. The heating current to this element is suitably controlled by a rheostat (not shown). As best illustrated in Fig. 2, the element 28 is positioned below the right-hand portion of theevaporator pipe 21 but the intermediate portion of the element is bent upward and away from the evaporator pipe until the left-handed portion of the element, extends generally parallel to one edge of the trough 25 (Fig. 3). By this arrangement of the heating element, the aqua ammonia is heated sufliciently to drive off the greater part of the ammonia gas therein while the residue can be separately heated to any desired degree to drive off water vapor in amounts necessary to satisfy the moisture requirements in the developing chamber.

In accordance with a modified form of the invention, the pipe 21 is provided with wick 30 (Fig. 4) of asbestos or the like, preferably coexistensive in length with that portion of the pipe 2! which extends upward toward the left in Fig. 2. By the use of the wick 30, the aqua ammonia is fed along the pipe by capillary action. The extensive area of the wick affords a large surface for effecting evaporation of the aqua ammonia while the residue thereof is discharged into the tray 25 as described above. I

A further modified form of the invention is illustrated in Figs. 6 and '7. In this form, evap oration of the aqua ammonia and water vapor are effected in an evaporator in which the perforated portion of the pipe 21 is replaced by a tray 3| which is upwardly inclined toward the left (Fig. 6) to discharge at its left end in a tray 25 of the construction previously described; The heater element which has been omitted from Fig. 6, is arranged in the manner shown in Fig. 1. The trays 25 and 3| are each provided with a strip of asbestos such as 32 and 33 extending preferably along the inner bottom surface of its related tray for the entire length thereof. The wick 33 may extend over the left end of tray 3| as shown in Fig. 7. The aqua ammonia is delivered to the tray 3| by the stub pipe 21. The evaporation of the aqua ammonia in the tray 3| and the evaporation of water vapor in tray 25 will be obvious from the foregoing description.

The temperature in the development chamber, in part, is maintained by a top heater in the form of an electric heating element 34 which extends across the developing chamber above and in parallel relation with the evaporator tray. Since the developing chamber is located directly above the printer unit, heat from the light'source L of this last named unit, modifies the temperature within the development chamber. If the temperature around the developing chamber is not carefully controlled, this temperature may drop below the dew-point with the result that moisture will accumulate on the outside of the chamber and drip down on the printed sheet.

In order to maintain the proper temperature conditions within the cabinet and especially within the glass cylinder 6 of the printing unit, excess heat is withdrawn therefrom by an air exhaust system. This system comprises an exhaust fan (not shown) and an air duct 35, having branche communicating with the upper part of the cabinet as well as with the interior of the glass cylinder at the right end thereof.

It will thus be seen that the present invention provides a combined printing and developing machine in which the heat from the printing unit does not adversely affect the developing unit so that staining and crinkling of the finished photoprints is avoided at all speeds at which the machine is operated.

What I claim is:

.1. In an evaporator for generating ammonia gas and watervapor for use in a developing unit for a printed photosensitive sheet, a pipe perforated along its top, means for introducing aqua ammonia to one end of said pipe, the intermediate portion of said pipe being lower than the ends thereof whereby a pool of aqua ammonia is contained therein, a wick extending at least from said intermediate portion of the pipe to the other end thereof whereby an increased evaporating area is provided, a downwardly sloping tray into the high end of which said pipe discharges, and a heating element arranged to supply controlled heat in the region of said tray.

2. In a device of the class described, a developer chamber having an exposure area by which a printed photosensitive sheet can be developed, an aqua ammonia evaporator in said chamber by which ammonia is generated and supplied to the interior of the said chamber, said evaporator comprising an elongated closed container having a perforated wall extending generally in a horizontal direction from its supply end to its discharge end, a wick in said container extending to the discharge end thereof whereby an increased evaporating area is provided, means for supplying aqua ammonia to the supply end of said container, a generally horizontal trough under said container to receive the discharge therefrom, and a heating element in spaced relation to said trough and said container whereby the evaporation of ammonia, and water vapor both contained in aqua ammonia can be independently controlled.

3. In an evaporator for generating ammonia gas and water vapor for use in a developing unit for a printed photosensitive sheet, an elongated closed container having a perforated wall extending generally in a horizontal direction from its supply end to its discharge end, a wick in said container extending to the discharge end thereof whereby an increased evaporating area is provided, a tray below said container into which the residue of said aqua ammonia passes from the discharge end of said container, and a source of controlled heat adjacent said tray and said container.

4. In an evaporator for generating ammonia gas and water vapor for use in a developing unit for a printed photosensitive sheet, a pipe perforated along its length, means for introducing aqua ammonia to one end of said pipe, a wick extending at least from an intermediate portion of the pipe to the discharge end thereof whereby an increased evaporating area is provided, a downwardly sloping tray into which the discharge end of said wick discharges, and a heating element arranged to supply controlled heat in the region of said tray.

5. In a device of the class described, a developer chamber having an exposure area by which a printed photosensitive sheet can be developed, an aqua ammonia evaporator in said chamber by which ammonia is supplied to the interior of said chamber, said evaporator comprising an inclined trough, an evaporating pipe perforated at its upper side and extending along the trough to discharge into the upper end thereof, the intermediate portion of said pipe being lower than the ends thereof to maintain a pool of aqua ammonia therein, means for supplying aqua ammonia to said pipe, a heating element extending in spaced relation to said trough and said pipe, said spacing varying from one end of said trough to the other end thereof whereby the evaporation of ammonia and water vapor both contained in aqua ammonia can be independently controlled.

6. In an evaporator for supplying ammonia gas and water vapor to a developing unit for a printed photosensitive sheet, a pipe located in a heated region and perforated along its top, means for introducing aqua ammonia near one end of said pipe, the intermediate portion of said pipe being lower than the ends thereof whereby a pool of aqua ammonia is contained therein, a downwardly sloping tray, the other end of said pipe being arranged to overflow into the high end of such tray, and a heating element arranged to supply controlled heat in the region of said tray.

7. In an evaporator for supplyin ammonia gas and water vapor to a developing unit for a printed photosensitive sheet, a downwardly sloping trough, a pipe perforated along its top and extending above and in parallel relation to said trough, means for supplying aqua ammonia to one end of said pipe, said pipe having a dip therein to hold a pool of aqua ammonia, the other end of said pipe discharging into the high end of said trough, a pipe perforated along its top and extending from a point between the lower end of said trough and said pipe to an intermediate point on said trough and then along one edge of said trough to the region of the discharge end thereof.

FREDERICK G. WILDE.

REFERENCES CITED The following references are of record. in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,172,783 Alink et al Sept. 12, 1939 2,384,155 Brunk Sept. 4, 1945 FOREIGN PATENTS Number Country Date 632,452 France Oct. 4, 1927 

